20440643 has 2 divisors, whose sum is σ = 20440644. Its totient is φ = 20440642.

The previous prime is 20440639. The next prime is 20440649. The reversal of 20440643 is 34604402.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20440643 - 2² = 20440639 is a prime.

It is not a weakly prime, because it can be changed into another prime (20440649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10220321 + 10220322.

It is an arithmetic number, because the mean of its divisors is an integer number (10220322).

Almost surely, 2^20440643 is an apocalyptic number.

20440643 is a deficient number, since it is larger than the sum of its proper divisors (1).

20440643 is an equidigital number, since it uses as much as digits as its factorization.

20440643 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2304, while the sum is 23.

The square root of 20440643 is about 4521.1329332370. The cubic root of 20440643 is about 273.4207799061.

The spelling of 20440643 in words is "twenty million, four hundred forty thousand, six hundred forty-three".